Internal combustion engines, including diesel engines, gasoline engines, gaseous fuel-powered engines, and other engines known in the art exhaust a complex mixture of air pollutants. The air pollutants are composed of gaseous compounds, which include nitrogen oxides, carbon monoxide, and hydrocarbons, and solid particulate matter also known as soot. Due to increased awareness of the environment, emission standards have become more stringent, and the amount of gaseous compounds and particulate matter emitted from an engine may be regulated depending on the type of engine, size of engine, and/or class of engine.
One method that has been implemented by engine manufacturers to comply with the regulation of emissions has been to remove gaseous compounds and particulate matter from the exhaust flow of an engine using an exhaust treatment device. A typical exhaust treatment device generally includes a tubular housing having mounted therein a filter assembly designed to trap particulate matter and/or a catalyst to convert the gaseous compounds to innocuous gases. A first end cap with an integral inlet directs exhaust flow to the filter assembly, and a second end cap with an integral outlet directs exhaust flow away from the filter assembly. Depending on the size and shape of the filter and/or the geometry of the first and second end caps, pressure losses through the exhaust treatment device may be incurred that reduce the fuel efficiency of the associated engine. And, because these engines are often associated with vehicular applications, the pressure losses are typically the result of the size of shape of the exhaust treatment device due to tight space constraints within the vehicle's engine compartment.
Various filter and end cap designs have been proposed that attempt to reduce pressure losses within a space-conserving exhaust treatment device. For example, U.S. Pat. No. 5,144,797 (the '797 patent) issued to Swars on Sep. 8, 1992, describes a space-saving exhaust treatment device having a central treatment segment, an inlet segment communicated eccentrically with the central treatment segment, and an outlet segment communicated eccentrically with an opposing end of the central treatment segment. The central treatment segment is cylindrical and houses a honeycombed catalyst. The inlet and outlet segments are also cylindrical with a diameter about one-half to three-quarters of the central treatment segment's diameter. The inlet and outlet segments are oriented with respect to the central treatment segment at angles of about 90°, with the outlet segment positioned opposite the inlet segment such that the direction of the exhaust flow through the inlet segment is substantially parallel to the direction of the exhaust flow through the outlet segment. The configuration of the exhaust treatment device forces the flow of exhaust to travel in a spiral and/or helical pattern through the exhaust treatment device to reduce noise. Because the exhaust treatment device acts to reduce noise, the size of and/or need for mufflers in an exhaust system containing the exhaust treatment device may also be reduced, thereby reducing pressure losses associated with these mufflers.
While the exhaust treatment device of the '797 patent may conserve space and help to reduce the pressure losses in an exhaust system, its applicability may be limited. More specifically, the shape of the exhaust treatment device of the '797 patent may limit its placement within a vehicle by requiring the outlet segment to protrude from the device in a direction opposite the protrusion of the inlet segment. And, the profile of the inlet and outlet segment bends and/or the helical flow-promoting surfaces may be sub-optimal, and could actually increase pressure losses in the exhaust flow.
The exhaust treatment device of the present disclosure solves one or more of the problems set forth above.